Despite high reported contraception use by U.S. adolescents, their pregnancy rates are among the highest in the industrialized world. In 2006, approximately 750,000 U.S. adolescents became pregnant. Inconsistent and incorrect contraceptive use is a significant direct cause of unintended pregnancy. Contraceptive methods that do not rely on the user are used more consistently and tend to be associated with lower discontinuation rates. Such methods, which include intrauterine contraceptive devices and implants, are collectively known as long acting reversible contraceptives (LARC). Yet only 2% of all contracepting U.S. women, and even fewer adolescents, utilize LARC methods. Increased use of LARC could ultimately decrease unintended pregnancy rates, including adolescent pregnancy rates. The Institute of Medicine's 2009 report of the 100 initial priority topics for comparative effectiveness research ranked strategies for preventing unintended pregnancy, including expanding access to LARC for young women, in the top quartile. Patient, provider and health systems issues all contribute to low LARC utilization. I recognize that in order to increase use of LARC, it is critical to examine all these issues. In this proposal, I will focus on provider behavior because data indicates that providers use unduly restrictive criteria with LARC. Additionally, my prior research has found that (1) female patients say their providers infrequently discuss LARC, and (2) clinicians themselves report they are unlikely to recommend IUDs to adolescents. I propose to utilize a mixed-method implementation science approach to determine primary care providers (PCPs) clinical practice with LARC for adolescents, identify barriers and facilitators to increasing LARC counseling and provision, then develop interventions designed to increase the proportion of PCPs who counsel and provide LARC to adolescents. I will systematically link formative research to intervention design, while applying theories and scientific evidence in the design process. Specifically, I plan to: (1) conduct qualitative interviews with urban PCPs to explore their experiences, attitudes and beliefs about LARC counseling and provision to adolescents; (2) develop a quantitative survey to measure PCPs reported LARC counseling and to ascertain associations between offering LARC, provider and practice characteristics; and (3) develop interventions to increase the proportion of PCPs who counsel about and provide LARC to adolescents in urban primary care. A multi-disciplinary mentoring and advisory team, as well as practical and didactic educational components of my career development plan, will foster my development as an independent health services researcher in the area of adolescent reproductive health. My long-term goal is to develop a R01 theory-driven, practice-based, comparative effectiveness interventions targeting PCPs in our established urban practice based research network and designed to increase LARC use in urban adolescents.